1. Field of the Invention
The present invention relates to an electrical connection box such as a fusible link block and, more particularly, to an electrical connection box having a simple structure and being capable of reducing costs.
2. Prior Art
As a conventional fusible link block, a fusible link block is disclosed in a publication "Japan Institute of Invention and Innovation Technical Disclosure" (issued Feb. 1, 1995; technical disclosure number 95-1451). The fusible link block described in FIG. 1 of this publication is constituted by a main cover, a bus-bar distributing board, and an under cover, and is designed to insert a fusible link thereinto.
In the main cover, a cavity in which an fusible link insertion portion is fitted is arranged on the upper surface side, and a bus-bar terminal fitting portion and an under cover fitting portion are arranged on the lower surface side through the bottom wall of the cavity. Male/female terminals are stored in the bus-bar terminal fitting portion and the under cover fitting portion, respectively. The male terminal portion of each male/female terminal passes through the bottom wall of the cavity to extend into the cavity, and the female portion is arranged in the bus-bar terminal fitting portion and the under cover fitting portion to face downward.
A bus-bar distributing board is attached to the opening surfaces of the bus-bar terminal fitting portion and the under cover fitting portion, and has a male terminal piece integrated with a bus bar (not shown), and has an insertion hole through which the upper end portion of an under cover passes and an insertion hole through which the upper end of a male terminal stored in the under cover.
When this fusible link block is used, the bus-bar distributing board is attached to the lower surface of the main cover, and the male terminal piece arranged on the bus-bar distributing board is fitted in the female terminal portion of the male/female terminal. The under cover is attached to the main cover from the lower surface side of the bus-bar distributing board, the upper end of the male terminal set in the under cover is fitted, through the insertion hole of the bus-bar distributing board, in the female terminal portion of the male/female terminal set in the main cover. In this manner, the fusible link block to which the fusible link is to be attached is completed.
In this state, the insertion portion of the fusible link is fitted in the cavity of the main cover to fit the female terminal in the fusible link and the male terminal portion of the male/female terminal in the main cover, thereby electrically inserting the fusible link between a bus-bar circuit and a circuit connected to the male terminal of the under cover.
Since the fusible link block described above uses male/female terminals to connect terminals to each other, costs tend to increase, and electrical connection performance may be degraded due to a large number of contact connection portions.
Therefore, in order to solve the above problem, a fusible link block described in the above publication with reference to FIGS. 2 and 3 is proposed.
This block is constituted by a main cover (first housing), a bus-bar distributing board, and an under cover (second housing). A male/female terminal is omitted in the main cover.
The main cover has a fitting cylinder portion having an upper surface side opening (one-direction opening) as a fitting port of the fusible link. The inside of the fitting cylinder portion is used as a cavity for fitting the fusible link, and a stopper for determining the insertion limit of the under cover is arranged at the upper end of the fitting cylinder portion. A lock portion corresponding to the under cover is formed on the outer peripheral wall of the main cover.
One side of a lower surface side opening of the fitting cylinder portion is kept open, the remaining side is closed by a bus-bar distributing board attachment portion. A bus-bar distributing board is attached to the lower surface of the bus-bar distributing board attachment portion.
The bus-bar distributing board has a male terminal integrated with a bus-bar, and the male terminal extends into the cavity. An opening is formed in the bus-bar distributing board.
The under cover has a bottom wall and an outer peripheral wall, and a lock arm which is to be locked in the lock portion in the main cover is formed on the outer peripheral wall. A columnar projecting portion extends from the upper surface of the bottom wall, and a fitting wall which passes through the opening of the bus-bar distributing board and is fitted into the cavity of the main cover is connected to the upper end of the columnar projecting portion. A fitting recessed portion for fitting an insertion portion of the fusible link is formed inside of the fitting wall. A guide wall having a height and a thickness which are adjusted to relatively small values constitutes one side of the fitting wall, and the guide wall is designed to be fitted in a central guide groove when the fusible link is inserted in the fusible link block.
A terminal insertion hole is arranged inside the columnar projecting portion, and a male terminal inserted into the terminal insertion hole from the lower direction is engaged by a lance, and the upper end portion of the male terminal extends into the fitting recessed portion.
When this fusible link block is used, the bus-bar distributing board is arranged inside the main cover, and the male terminal is extended into the cavity of the fitting cylinder portion. The under cover is attached to the main cover from the lower surface side of the bus-bar distributing board, and the fitting wall at the end of the columnar projecting portion of the under cover is fitted in the cavity of the main cover through the opening of the bus-bar distributing board.
In this manner, the male terminal arranged on the bus-bar distributing board and the male terminal of the under cover are arranged parallel to each other in the cavity, and the fitting cylinder portion and these terminals constitute a connector portion for attaching the fusible link. Thereafter, the fusible link is inserted into the connector portion to complete electrical connection of the fusible link.
According to this fusible link block, although the main cover and the under cover are used, the male terminal stored in the under cover is directly connected to the terminal of the fusible link. For this reason, the main cover requires no male/female terminal (intermediate connection terminal) arranged thereon, a simple structure can be obtained, and electrical connection performance.
Since terminals are partially constituted by the bus-bar distributing board, circuits such as a ground line which can be arranged common can be integrated at a high density, a simple structure can be obtained, and a reduction in cost can be performed. In particular, since the connector terminal is constituted by the male terminal stored in the under cover and the male terminal arranged on the bus-bar distributing board, like a general connector, the connector terminal can be advantageously connected to an opposite part without excessive wires.
However, in this fusible link block, since the lock portion and the lock arm are arranged at positions which are far from the fitting portion of the fusible link, the under cover is deflected downward when the fusible link is fitted. For this reason, a fitting operation of the fusible link may not be smoothly performed. In addition, a spare space is required to arrange the lock portion and the lock arm. When the lock portion is not properly fitted on the lock arm, the main cover is disconnected from the under cover. For this reason, a cumbersome checking operation must be performed.
In addition to the electrical connection box, utility model application laid open No. 58-23189 discloses a structure in which, a lock portion which is engaged with a lock portion formed in the end portion of a box is arranged on the outer surface of a connector for a fusible link when the connector is attached to the box.
However, in the structure described in this publication, the connector is attached to the lock portion formed on the end portion of the box, a coupling strength is disadvantageously low.